I do think the heat has an effect - I remember last year some members here found their levels rose a bit and others found that they came down. It's probably too early to tell, so as Eddy suggests see how it goes for a few days.

HbA1c at May 2017: 5.3 (=34)
HbA1c at May 2018: 5.8 (40)
HbA1c at Dec 2018: 5.4 (36)
HbA1c at May 2019: 5.5 (37): now considered in remission at surgery